Read only access to table scalar Measure columns. More...

#include <MBaseline.h>

Inheritance diagram for casacore::ScalarMeasColumn< M >:

Public Member Functions
	ScalarMeasColumn ()
	The default constructor creates a null object. More...

	ScalarMeasColumn (const Table &tab, const String &columnName)
	Create the ScalarMeasColumn from the table and column Name. More...

	ScalarMeasColumn (const ScalarMeasColumn< M > &that)
	Copy constructor (copy semantics). More...

virtual	~ScalarMeasColumn ()

void	reference (const ScalarMeasColumn< M > &that)
	Change the reference to another column. More...

void	attach (const Table &tab, const String &columnName)
	Attach a column to the object. More...

M	convert (rownr_t rownr, const M &meas) const
	Get the Measure contained in the specified row and convert it to the reference and offset found in the given measure. More...

M	convert (rownr_t rownr, const MeasRef< M > &measRef) const
	Get the Measure contained in the specified row and convert it to the given reference. More...

M	convert (rownr_t rownr, uInt refCode) const

const MeasRef< M > &	getMeasRef () const
	Returns the column's fixed reference or the reference of the last read Measure if references are variable. More...

void	setDescRefCode (uInt refCode, Bool tableMustBeEmpty=True)
	Reset the refCode, offset, or units. More...

void	setDescOffset (const Measure &offset, Bool tableMustBeEmpty=True)

void	setDescUnits (const Vector< Unit > &units, Bool tableMustBeEmpty=True)


void	get (rownr_t rownr, M &meas) const
	Get the Measure contained in the specified row. More...

M	operator() (rownr_t rownr) const


void	put (rownr_t rownr, const M &meas)
	Put a Measure into the given row. More...

Public Member Functions inherited from casacore::TableMeasColumn
	TableMeasColumn ()
	The default constructor creates a null object. More...

	TableMeasColumn (const Table &tab, const String &columnName)
	Create the ScalarMeasColumn from the table and column Name. More...

	TableMeasColumn (const TableMeasColumn &that)
	Copy constructor (copy semantics). More...

virtual	~TableMeasColumn ()

void	reference (const TableMeasColumn &that)
	Change the reference to another column. More...

void	attach (const Table &tab, const String &columnName)
	Attach another column to the object. More...

Bool	isDefined (rownr_t rownr) const
	Tests if a row contains a Measure (i.e., if the row has a defined value). More...

const TableMeasDescBase &	measDesc () const
	Get access to the TableMeasDescBase describing the column. More...

TableMeasDescBase &	measDesc ()

Bool	isNull () const
	Test if the object is null. More...

void	throwIfNull () const
	Throw an exception if the object is null. More...

const String &	columnName () const
	Get the name of the column. More...

Table	table () const
	Get the Table object this column belongs to. More...

Bool	isScalar () const
	Is the column a scalar measures column? It is if the underlying column is a scalar column or an array column with a fixed 1-dimensional shape. More...

Protected Member Functions
MeasRef< M >	makeMeasRef (rownr_t rownr) const
	Make a MeasRef for the given row. More...

Private Member Functions
ScalarMeasColumn &	operator= (const ScalarMeasColumn< M > &that)
	Assignment makes no sense in a readonly class. More...

Bool	equalRefs (const MRBase &r1, const MRBase &r2) const
	Check if refs have the same value (as opposed to being the same object). More...

void	cleanUp ()

Private Attributes
Bool	itsConvFlag

ArrayColumn< Double > *	itsArrDataCol

ScalarColumn< Double > *	itsScaDataCol

ScalarColumn< Int > *	itsRefIntCol

ScalarColumn< String > *	itsRefStrCol

ScalarMeasColumn< M > *	itsOffsetCol

MeasRef< M >	itsMeasRef

Additional Inherited Members
Protected Attributes inherited from casacore::TableMeasColumn
uInt	itsNvals

CountedPtr< TableMeasDescBase >	itsDescPtr

TableColumn	itsTabDataCol

Bool	itsVarRefFlag

Bool	itsVarOffFlag

Detailed Description

template<class M>
class casacore::ScalarMeasColumn< M >

Read only access to table scalar Measure columns.

Intended use:

Public interface

Review Status

Reviewed By:: Bob Garwood
Date Reviewed:: 1999/12/23
Test programs:: tTableMeasures

Prerequisite

Synopsis

ScalarMeasColumn objects can be used to access scalar Measure Columns in tables, both for reading and writing (if the table is writable).

Before a column can be accessed it must have previously been defined as a Measure column by use of the TableMeasDesc object.

The ScalarMeasColumn class is templated on Measure type. Typedefs exist in the various Measure classes (e.g. MEpoch) to make declaration less long winded. Constructing scalar Measure column objects using these typedefs looks like this:

MEpoch::ScalarMeasColumn ec(table, "ColumnName);

Reading and writing Measures

The reading and writing of Measures columns is very similar to reading and writing of "ordinary" Table columns. get() and operator() exist for reading Measures and the put() member for adding Measures to a column. (put() is obviously not defined for ScalarMeasColumn objects.) Each of these members accepts a row number as an argument. The get() function gets the measure with the reference and offset as it is stored in the column. Furthermore the convert() function is available to get the measure with the given reference, possible offset, and possible frame

When a Measure is put, the reference and possible offset are converted if the measure column is defined with a fixed reference and/or offset. If the column's reference and offset are variable, the reference and offset of the measure as put are written into the appropriate reference and offset columns.

Example

// This creates a Scalar MEpoch column for read/write access.  Column
// "Time1" must exist in Table "tab" and must have previously been
// defined as a MEpoch column using a TableMeasDesc.
MEpoch::ScalarMeasColumn timeCol(tab, "Time1");
// print some details about the column
if (timeCol.measDesc().isRefCodeVariable()) {
cout << "The column has variable references." << endl;
} else {
cout << "The fixed MeasRef for the column is: "
<< timeCol.getMeasRef() << endl;
}
// Add tab.nrow() measures to the column.  
MEpoch tm(Quantity(MeasData::MJD2000, "d"), MEpoch::TAI);
for (rownr_t i=0; i<tab.nrow(); i++) {
timeCol.put(i, tm);
}
// We could read from the column using timeCol but instead a read
// only column object is created.
MEpoch::ScalarMeasColumn timeColRead(tab, "Time1");
for (i=0; i<tab.nrow(); i++) {
cout << timeColRead(i) << endl;
}

Motivation

The standard Casacore Table system does not support Measures columns. This class overcomes this limitation.

Thrown Exceptions

AipsError during construction if the column specified variable offsets which are stored in an Array- rather than a ScalarColumn.

Definition at line 46 of file MBaseline.h.

Constructor & Destructor Documentation

template<class M>

casacore::ScalarMeasColumn< M >::ScalarMeasColumn ( )

The default constructor creates a null object.

Useful for creating arrays of ScalarMeasColumn objects. Attempting to use a null object will produce a segmentation fault so care needs to be taken to initialize the objects first by using attach(). An ScalarMeasColumn object can be tested if it is null by using the isNull() member.

template<class M>

casacore::ScalarMeasColumn< M >::ScalarMeasColumn	(	const Table &	tab,
		const String &	columnName
	)

Create the ScalarMeasColumn from the table and column Name.

template<class M>

casacore::ScalarMeasColumn< M >::ScalarMeasColumn ( const ScalarMeasColumn< M > & that )

Copy constructor (copy semantics).

template<class M>

virtual casacore::ScalarMeasColumn< M >::~ScalarMeasColumn ( )

virtual

Member Function Documentation

template<class M>

void casacore::ScalarMeasColumn< M >::attach	(	const Table &	tab,
		const String &	columnName
	)

Attach a column to the object.

template<class M>

void casacore::ScalarMeasColumn< M >::cleanUp ( )

private

template<class M>

M casacore::ScalarMeasColumn< M >::convert	(	rownr_t	rownr,
		const M &	meas
	)		const

inline

Get the Measure contained in the specified row and convert it to the reference and offset found in the given measure.

Definition at line 177 of file ScalarMeasColumn.h.

Referenced by casacore::ScalarMeasColumn< casacore::MDoppler >::convert().

template<class M>

M casacore::ScalarMeasColumn< M >::convert	(	rownr_t	rownr,
		const MeasRef< M > &	measRef
	)		const

Get the Measure contained in the specified row and convert it to the given reference.

template<class M>

M casacore::ScalarMeasColumn< M >::convert	(	rownr_t	rownr,
		uInt	refCode
	)		const

template<class M>

Bool casacore::ScalarMeasColumn< M >::equalRefs	(	const MRBase &	r1,
		const MRBase &	r2
	)		const

private

Check if refs have the same value (as opposed to being the same object).

template<class M>

void casacore::ScalarMeasColumn< M >::get	(	rownr_t	rownr,
		M &	meas
	)		const

Get the Measure contained in the specified row.

It returns the Measure as found in the table.

template<class M>

const MeasRef<M>& casacore::ScalarMeasColumn< M >::getMeasRef ( ) const

inline

Returns the column's fixed reference or the reference of the last read Measure if references are variable.

Definition at line 189 of file ScalarMeasColumn.h.

template<class M>

MeasRef<M> casacore::ScalarMeasColumn< M >::makeMeasRef ( rownr_t rownr ) const

protected

Make a MeasRef for the given row.

template<class M>

M casacore::ScalarMeasColumn< M >::operator() ( rownr_t rownr ) const

template<class M>

ScalarMeasColumn& casacore::ScalarMeasColumn< M >::operator= ( const ScalarMeasColumn< M > & that )

private

Assignment makes no sense in a readonly class.

Declaring this operator private makes it unusable.

template<class M>

void casacore::ScalarMeasColumn< M >::put	(	rownr_t	rownr,
		const M &	meas
	)

Put a Measure into the given row.

template<class M>

void casacore::ScalarMeasColumn< M >::reference ( const ScalarMeasColumn< M > & that )

Change the reference to another column.

template<class M>

void casacore::ScalarMeasColumn< M >::setDescOffset	(	const Measure &	offset,
		Bool	tableMustBeEmpty = `True`
	)

template<class M>

void casacore::ScalarMeasColumn< M >::setDescRefCode	(	uInt	refCode,
		Bool	tableMustBeEmpty = `True`
	)

Reset the refCode, offset, or units.

It overwrites the value used when defining the TableMeasDesc. Resetting the refCode and offset can only be done if they were defined as fixed in the description.
Tip: In principle the functions can only be used if the table is empty, otherwise already written values have thereafter the incorrect reference, offset, or unit; However, it is possible that part of the table is already written and that the entire measure column is filled in later; In that case the reference, offset, or units can be set by using a False tableMustBeEmpty argument;

template<class M>